Engine-Codes - Hyundai - P0128 HYUNDAI

P0128 HYUNDAI - Coolant Thermostat

Repair Importance Level: 3/3
Repair Difficulty Level: 2/3  What is this?
Table of contents

P0128 HYUNDAI Possible Causes

  • Leaking or stuck open thermostat
  • Low engine coolant level
  • Insufficient warm up time
  • Faulty engine coolant temperature sensor
  • Engine coolant temperature sensor harness is open or shorted
  • Engine coolant temperature sensor circuit poor electrical connection

How is the P0128 HYUNDAI code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Tech Notes

If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem.

What is the cost to diagnose the P0128 HYUNDAI code

Labor: 1.0

The cost to diagnose the P0128 HYUNDAI code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

When is the code detected?

The engine coolant temperature does not reach to specified temperature even though the engine has run long enough.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P0128 HYUNDAI Meaning

Coolant thermostat (coolant temperature below thermostat regulating temperature). Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.

More Information

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